Hi Wim,
I think that TCP/IP protocol is the best solution for you.
It is fast and reliable.
In LV there's a nice example for multi-client connection:Date Server.vi and Date Client.vi, you find them in tcp/ip examples.
If the client needs only a portion of your image, you can build a bi-directional communication where the client sends a command to the server that sets which part of image it should send. In this way you reduce the amount of data shared and speed-up the communication.
Let me know if you need some more help.
Good luck,
Alberto